Optical media types

 

Five categories of optical media are available to meet most storage requirements: CD-ROM, DVD-ROM, DVD-RAM, write-once read-many (WORM) optical cartridges, and erasable optical cartridges.

• CD-ROM is a read-only format that is optimized for read performance. CD-ROMs are ideal for wide-scale distribution of programs and data. The CD-ROM data format is identical to the one that is used with personal computers. This makes it possible to develop CD-ROMs for use in both personal computers and the system. You can read CD-ROMs in either a CD-ROM or DVD drive.

• DVD-ROM is a read-only format that provides a higher capacity than CD-ROM. Like CD-ROM, DVD-ROMs are excellent for wide-scale distribution of programs and data. You can only read DVD-ROMs in a DVD drive.

• DVD-RAM is writable optical media that is available in both double-sided (Type I) and single-sided (Type II) formats, ranging from 2.6 GB per cartridge to 9.4 GB per cartridge. Both types can be accessed in a DVD-RAM drive, and Type II media can be read in a DVD-ROM drive when the media is removed from the cartridge.

• WORM storage is an economical way to archive data, yet still have it quickly and easily accessible. WORM media is available in 1x (650 MB), 2x (1.3 GB), 4x (2.6 GB), 8x (5.2 GB), and 14x (9.1 GB or 8.6 GB) capacities. It is also available in 30 GB Ultra Density Optical (UDO).

• An erasable cartridge offers the most flexibility with similar capabilities as magnetic storage. Erasable media is available in 1x (650 MB), 2x (1.3 GB), 4x (2.6 GB), 8x (5.2 GB), and 14x (9.1 GB or 8.6 GB) capacities. It is also available in 30 GB Ultra Density Optical (UDO).

Both WORM and erasable cartridges must have a sector size of 1024 bytes per sector for 1x, 2x, and 4x media. For 8x media, permanent WORM must have a sector size of 2048. Continuous composite write-once (CCW), WORM, and erasable media can either be 1024 or 2048 bytes per sector. 14x media is available in CCW and erasable in 2048 or 4096 bytes per sector. UDO media is available in 8192 bytes per sector.

• Directly attached optical media libraries
  One method of connecting optical media libraries is to directly connect the optical media library to your system. A multiwire cable connects the library to an IOP or I/O adaptor card.
• Optical system configurations
  All systems include a rack-mounted CD-ROM or DVD-ROM drive that is ideal for program and data distribution.

 

Parent topic:

Optical devices